Squirrel 450/850 series datalogger

452 / 852 Models

4 or 8 Multi-purpose inputs

The Squirrel 450/850 series is a cost effective portable data logger with a maximum of 4 or 8 inputs. In common with its bigger brother, the Squirrel 1000 series data logger, it is equipped with impressive specifications, long battery life and a three year guarantee. Models 451 and 851 have 4 or 8 universal inputs respectively, configurable for voltage, current and temperature for both thermocouple and thermistor sensors. In addition a serial interface is available for special applications, including Vaisala weather sensors WMT52 & WXT520.

Common Features

All models feature panel mounted controls (except the 401) and a 2 line, 32 character LCD readout for setting up, monitoring and reading recorded events on the logger. Resolution is 12 bit with standard thermistor, thermocouple and DC voltage or current inputs. Two sensor power outputs are available to power external sensors - such as humidity probes.

EU Range
In addition "EU" range is standard, enabling the logger to independently rescale each input to a user defined engineering unit, e.g. humidity can be displayed as 0 to 100% RH, permitting quick and unambiguous understanding of the readings on the display.

Internal memory
The logger is fitted as standard with 250K of memory, backed up by a lithium battery, and at least 250,000 locations are available for data storage. Note that this refers to data storage, not bytes, as 2 bytes of conventional memory are used for every reading. Larger memory can be field fitted by a competent engineer as an option.

Sensors for the 450 Series Squirrel

Sensors providing the industry standard 4-20mA output are accommodated enabling many parameters to be logged, for example, Meteorological sensors (anemometer, rain precipitation, barometric pressure).

The 450/850 Series Range Of Models

The current 450/850 series consists of the following models, each offers a wide variety of user applications:

Model Inputs Features
451 / 851 4 / 8 channels Each channel configurable for:
  • Temperature (thermistor or thermocouple)
  • Voltage
  • Current
451L / 851L 4 / 8 channels Each channel configurable for:
  • Temperature (thermistor or thermocouple)
  • Voltage (includes a +/- 10mv range ideal for use with Huxseflux heat flux sensor)
  • Current
451T / 851T 4 / 8 channels 0.1sec interval (fast recording feature)
452 / 852 4 / 8 pulse only
451WXT/WMT 4 universal + 1 serial Serial input for Vaisala WXT520 / WMT52 weather sensor*
851WXT/WMT 8 universal + 1 serial Serial input for Vaisala WXT520 / WMT52 weather sensor*

Weather sensors

Vaisala sensors can be powered by the logger batteries/supply. Eltek can supply the Vaisala sensors if required.

Options - Factory installed

Pulse input

The 451/851 only is available with two pulse inputs

Text message on alarm

Optional Text message on alarm using and /or remote access, using external GSM modem.

Options - Field installed

Memory expansion

The memory can be expanded to 2M readings (about 2,080,000).

Don't forget that a lot of memory takes time to download and that it is possible to reduce the amount of memory used for a logging run. Eltek loggers download at 38400 baud, and in practice this is about 500 readings per second.


Accuracy (at 20ºC): Voltage/Current:
±0.1% of reading ±0.1% of span
±0.1% of reading ±0.1% of span
Environment: Ambient temperature: -30ºC to 65ºC
Humidity: up to 95% (non condensing)
Power Supplies: Internal: Six AA manganese alkaline batteries (9V nominal)
External: 9-14V DC at 100mA.
Battery Life: At least 6 months with all channels recording every 5 minutes
Clock Accuracy: 1 second/day at 20ºC
Physical details: Dimensions (mm): H 120, W 180, D 62
Weight, inc batteries: Approximately 1Kg
Material: ABS coated with durable NEXTEL finish
Interface: RS232C at up to 38,400 Baud
Connectors: RS232 Output:
6 pin female mini-DIN
3 pin ST Plug (5mm pitch "screw Terminal")
Input impedance: Voltage and Thermocouple: 1M Ohms
Current: 10 Ohms
Sensor power outputs: Internally selectable to 5V regulated or Squirrel supply voltage.


Input type Available ranges Resolution
Thermistor -50 to 150ºC 0.1C
Thermocouple - Type K 0 to 900ºC 0.5C
Thermocouple - Type K -200 to 450ºC 0.2C
Thermocouple - Type T -200 to 350ºC 0.2C
Voltage 0 to 50mV 50µV
0 to 100mV 50µV
0 to 200mV 50µV
0 to 500mV 0.5mV
0 to 1V 0.5mV
0 to 2V 0.5mV
0 to 5V 5mV
0 to 10V 5mV
0 to 20V 5mV
-25 to 25mV 50µV
-50 to 50mV 50µV
-100 to100mV 50µV
-250 to 250mV 0.5mV
-500 to 500mV 0.5mV
-1 to 1V 0.5mV
-2.5 to 2.5V 5mV
-5 to 5V 5mV
-10 to 10V 5mV
Current 4 to 20mA 0.05%
0 to 20mA 5µA


Product datasheet:

450/850 Series datasheet

Product manual

450/850 & 1000 Series Manual